The invention relates to a unit for conveying fuel.
One such unit is known from German Patent Disclosure DE 40 20 521 A1. This unit has a flow pump, which has an impeller revolving in a pump chamber as its conveying means. The pump chamber is formed by an intake cap that closes off the pump housing on the intake side and by an intermediate housing. Such housing parts are usually made from metal, preferably anodized aluminum. The conveying means revolving between the housing parts is made from plastic and contains embedded glass fibers elements in order to increase its strength. After even a short period of operation, increased wear can occur in a flow pump of this kind. Dirt brought in from outside, especially, can cause abrasion of the anodized aluminum layer and of the surface of the impeller.
German Utility Model DE-U 91 02 825 also discloses a unit for conveying fuel, which has a pump chamber in which at least parts of the multiple-part pump housing are produced from ceramic material. By this means a wear-resistant wall of the pump chamber can be created which moreover is capable of lessening the development of irritating and undesired noise. This kind of pump chamber is provided in internal gear pumps. Because of the geometrically simply designed housing parts for forming a pump chamber of the internal gear pump, simple and economical production from ceramic is possible. This is not true for flow pumps, since the housing parts that form the pump chamber have a relatively complicated geometrical design.